1. Field of the Invention
This invention pertains to bending angle stock, and particularly to tools and methods for bending angle stock such as is used for supporting tubing, wires, cable and the like.
2. Description of the Related Art
In industrial and commercial applications, angle stock having standard dimensions such as 2 inch by 2 inch sides is installed to receive, hold and support lines, including pneumatic tubing, electric wires, and fiber optic cable, which are fastened to the angle stock with clips and bolts. Such angle stock is commercially available in lengths ranging typically up to about twenty feet and in a variety of materials of construction including iron, galvanized iron, and aluminum.
As an example of an industrial application, angle stock is installed in a chemical plant, petrochemical plant or refinery for receiving pneumatic instrument tubing or electrical wire used for control of equipment and machinery. The angle stock is supported by stanchions or is attached to pipe racks and the like. It is frequently necessary to run long lengths of angle stock to provide support for various lines, and to do so, it is necessary to make numerous bends in the angle stock.
A bend in angle stock along a desired bend line has been made by first cutting appropriate clearance notches and manually bending one end of the angle stock toward the other end at the desired bending point to form either an "outside" or an "inside" bend. Bending has been accomplished by hand or with the assistance of a vise and hammer. When angle stock is bent by hand without the aid of any tool, the angle stock may not bend to form a clean angle in each side adjacent to the desired bend point.
A clean bend has been obtained by using a vise to squeeze and straighten a side adjacent the bend or by using a vise and hammer to straighten a side adjacent the bend. Although straight sides are not essential for function and performance of the angle stock as a support tray, the neat appearance of a clean bend with straight lines is considered desirable and thus time is typically spent to achieve a neat appearance.
A problem with such bending is that a vise is required, and a vise must be mounted to a support. Angle stock is frequently installed as a field application where use of a vise is not convenient. Although a vise can be mounted on a truck, and the truck can be driven to the work site, the point of installation may be in a pipe rack, for example, which requires numerous trips up and down a ladder between the point of installation and the vise. Further, when working with a twenty-foot piece of angle stock, it is cumbersome to use a vise and hammer to bend the angle stock. In addition to such bending operations not producing crisp bends and straight sides in the angle stock, such manual bending is time-consuming and often requires more than one worker.
Alternatively, fitting angles are commercially available for assembling an angled joint between two straight pieces of angle stock. However, industrial parts such as these are expensive, and it is time consuming to assemble fitting angles. Further, a fitting angle is not as strong as a bent angle, such as described above, because the bent angle is formed in an integral piece of angle stock, while the fitting angle is an assembly of two pieces of angle stock with a fitting in between. Non-integral fitting angles are bolted together, and the bolts have a tendency to work loose over time, which effectively disassembles the fitting angle.
Angle stock installed in industrial applications such as in chemical plants, is subjected to a considerable amount of vibration which tends to work the bolts loose in the fittings. It is not unusual to see missing bolts and loose joints in such applications after a period of time has elapsed since installation. In such instances, the line that was initially supported, such as a pneumatic instrument line, is no longer supported and is consequently subject to failure. Two problems are thus inherent in using prefabricated fitting angles--the fittings are expensive and they work loose, leaving the line secured to the angle stock unsupported. On the other hand manual bending of angle stock to form a clean, crisp bend requires a vise and hammer, which is inconvenient and cumbersome to use.